Summary: Ordered for use with ACOPOWER 40A Midas MPPT Controller. An external sensor allows the temperature to be measured away from the MPPT, either on batteries or on a solar panel (or somewhere else, maybe on a device). Pros: Good fit and finish. but the seller answered my question with 3 meters. Both ends of the cable don't seem to be very waterproof, probably wrap tape around both ends to seal it better. Conclusion: 4 stars for 15€.